FWIW - we are currently rebuilding a multi generational setup and are not really changing too much.
I would strongly vote for the bud box over the tub. Also, if you can work cows back in the direction they came from (chute pointing back towards incoming alley) things are much quicker and easier - especially with one person).
Alleyways around 12' are about right for sorting on foot, a bit wider for horse work.
We got a book from
onemancorrals.com that has some good stuff, and we are building with steel pipe and 7/8 sucker rod using clamps our neighbour sells. It is cheaper than panels by a lot, much sturdier, and faster than welding. As well, if a cow gets hung up, you undo some nuts rather than busting out the cutting torch. You can also add rails or re-space them quickly and easily.
The only other thing I would say is to spend money on good gates, and quite a few of them. The flexibility is worth the $.
We use a seperate budbox/alley for our loading chute and I would never do it any other way. Since no one gets paid without shipping cattle out, this is a big priority in my mind. We built a solid loading chute and filled it to grade with gravel. The cattle like the footing and load really well.
The one splurge we have done is to purchase an alley and squeeze, and I may run some air line to have an air cylinder operated gate at the end of the chute for sorting.
Also to save $, we have built larger holding pens out a bit further with wire panels, and then further out again with electric wire. Works good to enable lots of cattle to go through without pressure and crowding, and it only takes 5 minutes to bring up a larger draft from the holding area when you are done the ones you are working on.